Recurrence of Hypophysitis After Immune Checkpoint Inhibitor Rechallenge

Immune checkpoint inhibitor (ICI)-induced hypophysitis is an immune-mediated pituitary inflammation that tends to cause long-term pituitary deficiency. Management of ICI-induced hypophysitis includes corticosteroids for acute inflammation and long-term hormone replacement due to irreversible pituitary cell damage. We report a case of recurrent hypophysitis following ICI rechallenge for metastatic melanoma. A 33-year-old woman with recurrent metastatic melanoma with adrenal, pelvic, and inguinal metastases developed recurrent hypophysitis during treatment with ipilimumab and nivolumab which recurred with rechallenge >5 years later. In both cases, headache was the most notable symptom and brain MRI showed pituitary enlargement and edema without evidence of metastases. Central adrenal insufficiency and symptoms caused by mass effect were treated with acute high-dose corticosteroids and long-term replacement corticosteroids. Based on recurrence and failure of symptomatic treatment with continued steroid treatment, ICI was discontinued. This case illustrates that hypophysitis may recur with ICI rechallenge, challenging traditional assumptions that chronic, irreversible irAEs are unlikely to recur or flare. The regenerative potential of pituitary cells after ICI-induced damage or additional damage to previously unaffected cells may be more conceivable than previously realized. Additional research on the potential for recurrent ICI-induced endocrinopathies are needed.